Class 4 - Attention 2 Flashcards
Visual Search
finding a specific stimulus in a mix of multiple stimuli
Conjunction search
a search for an object in an array that combines two or more features
Pop- Out search
a search for an object in an array that can be identified by one feature
Conjunction search vs pop-out search reaction time
Longer for conjunction
set size
items in visual array
matters for conjunction but not pop-out
Visual attention in conjunction searches modulates
visuospatial attention in a similar way to endogenous cuing
probe at relevant item
larger P1 (same with ponor (?) viewing task)
Cuing attention to particular spot
enhance level of neural activity in response to a stimulus that appears in this spot (saw with ERP- group of neuronal activity)
V4 neurons
color sensitivity
no longer attentionally attending to preferred stimulus (V4 neuron - single neuron)
still responding but at a lower rate
put second stimulus in same receptive field
sensory interaction - overall reduction in spikes per second
When attention is payed outside of receptive field
No attentional modulation found
Move attention to particular stimulus within the receptive field the second stimulus
no longer reduces level of activity - no longer competition between the two stimuli
Biased competition model
Attention resolves competition between events in receptive field
receptive field size and biased competition model
larger RF - more competition can occur
early visual cortex - fields too small to include more than one stimuli
grater need for attention to focus on stimulus as
go further from V1
Parahippocampal place area (PPA)
sensitive to sense/ places
Attention to places
increase activity to PPA compared to baseline
focus on text
increase in activity of visual word form area
Networks of attention
three:
- Alerting
- Orting
- Executive
Tend to be related with different neurotransmitters
Alerting network of attention
maintaining sensitivity to incoming information
Orienting network of attention
aligning attention with sensory input, selecting among sensory inputs
Executive network of attention
modulating of attentional activity by goals
Network of attention complementary to three network system
Dorsal fronto-parietal network
Ventral fronto-parietal network
Dorsal fronto-parietal network
directed towards:
Involves:
Preparing and applying goal-directed (top-down) selection
Intraparietal cortex and superior frontal cortex (including frontal eye fields)
Ventral fronto-parietal network
Directed towards:
Involves:
Detection of behaviorally relevant stimuli (bottom-up)
Temporoparietal cortex and inferior frontal cortex
Mainly right-lateralized
More active - when drop something, is something dangerous ? etc.
Frontal eye fields coordinate
eye movements and shifts of gaze
Direction of gaze from FEF to other visual areas modulates
level of activity
Stimulus not present but attention directed to area
no activity in V4 (b/c no stimulus) fair amount of activity in FEF - in anticipation of a stimulus
stimulate activity in FEF (via TMS) modulate activity
in area MT and FFA
Spatial neglect/hemi neglect
A failure to acknowledge, explore, or respond to stimuli located on contralesional side of space
most of time due to damage in right hemisphere - exiperenced as Left hemi neglect
Typically expressed by ‘ignoring’ left side of objects - not incapable of noticing on left size - just not able to incorporate it
Letter cancelation test
cancel out letter told to - only cross out A on one side - hemi neglect
spatial neglect is not
a primary sensory (visual) or memory deficit per se
this can be seen when patient is asked to imagine a scene - only name things on R side from where standing
spatial neglect can be modulated by
motivation
Localization of neglect can look similar to ___ but not __
visual cortical lesions but not cortically blind
Bálint’s syndrome
A profound disorder of visual attention with several parts: Simultagnosia, Optic ataxia, Ocular apraxia
Simultagnosia
inability to perceive more than one object at a time during a single fixation
Optic ataxia
misreaching for objects
Ocular ataxia
disorganization of voluntary eye movements
Localization of neglect lesion location
Lesions of control systems
- Inferior parietal, superior temporal areas (at junction of these two)
can observe unilateral spatial neglect by
observing eye patterns
neglect patients show pattern of movement biased in the direction of the right visual field.
patients with neglect __ copy an image and cannot ___ from memory
cannot copy and cannot draw from memory
spatial neglect not only applies to sensory world but also
in remembering a scene
(ex. imagine looking at a building and then looking from the building)
extinsion in spatial neglect is a __
failure to perceive or act on contralesional stimulus due to the presence of competing stimulus in ipsilateral hemifield (which prevents patient from detecting the contralesional stimulus)
Neglect is __ while Balint is
unilateral lesion, bilateral lesion.
extinsion in spatial neglect shows
that sensory inputs are competitive
Late selection model
perceptual system processes all inputs than selection takes place
early selection model
stimulus can be selected for further processing or thrown out as irrelevant for further processing
selection model
mix of both early and late selection (attention involved in early selection and reflective (coattail party effect) in late selection)
endogenous cuing
orientating of attention to the cue is voluntary and driven by goals (focus on dot)
exogenous cuing
automatic capture of attention (flash of light)
cost of attention
when something occurs at an unexpected location
first big ERP wave
positive polarity - P1
biased competition model for selective attention
different stimuli in a visual seen fall within the receptive field of a neuron, bottom up signals compete to control neuron firing, attention helps resolve competition
the higher up in visual hierarchy the
greater chance for competition because visual fields are larger- thus a greater need for attention
perigeniculate nucleus
proton of thalamic reticular nucleus (TRN) that surrounds the lateral geniculate nucleus (LGN)
is large neuronal projections from here to V1 - TRN circuitry
highly focused visual spatial attention can modulate
activity in the thalamus via the perigeneculate nucleus
Attention involves either activating or inhibiting signal transmission from the __ to the ___ via the ___
descending neural signal from cortex or signal from subcortical inputs travel to __ that ___, and ____ information transmission form the __ to the ___
also the inputs can __
LGN to the visual cortex by the TRN circuitry
TRN neurons that excite TRN neurons and inhibit information transmission from the LGN to the visual cortex
inputs can suppress TRN neurons, increasing transmission from LGN to visual cortex
Inhibition of return
IOR - so that we do not hyperfixate on one thing
feature integration theory of attention
spatial attention must be directed to relevant stimuli in order to integrate features into a perceived object and it must be deployed in a serial manner for each item in the array - this is necessary to link the information in the different feature maps so that the target can be analyzed and identified
- for conjunction search
conjunction search affects the __ wave in a similar way that __ does
P1, cued spatial attention does
(increases firing)
